source: trunk/src/corelib/tools/qpair.qdoc@ 846

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1/****************************************************************************
2**
3** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
4** All rights reserved.
5** Contact: Nokia Corporation ([email protected])
6**
7** This file is part of the documentation of the Qt Toolkit.
8**
9** $QT_BEGIN_LICENSE:FDL$
10** Commercial Usage
11** Licensees holding valid Qt Commercial licenses may use this file in
12** accordance with the Qt Commercial License Agreement provided with the
13** Software or, alternatively, in accordance with the terms contained in a
14** written agreement between you and Nokia.
15**
16** GNU Free Documentation License
17** Alternatively, this file may be used under the terms of the GNU Free
18** Documentation License version 1.3 as published by the Free Software
19** Foundation and appearing in the file included in the packaging of this
20** file.
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22** If you have questions regarding the use of this file, please contact
23** Nokia at [email protected].
24** $QT_END_LICENSE$
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26****************************************************************************/
27
28/*!
29 \class QPair
30 \brief The QPair class is a template class that stores a pair of items.
31
32 \ingroup tools
33
34 QPair\<T1, T2\> can be used in your application if the STL \c
35 pair type is not available. It stores one value of type T1 and
36 one value of type T2. It can be used as a return value for a
37 function that needs to return two values, or as the value type of
38 a \l{Container classes}{generic container}.
39
40 Here's an example of a QPair that stores one QString and one \c
41 double value:
42
43 \snippet doc/src/snippets/code/doc_src_qpair.qdoc 0
44
45 The components are accessible as public data members called \l
46 first and \l second. For example:
47
48 \snippet doc/src/snippets/code/doc_src_qpair.qdoc 1
49
50 QPair's template data types (T1 and T2) must be \l{assignable
51 data types}. You cannot, for example, store a QWidget as a value;
52 instead, store a QWidget *. A few functions have additional
53 requirements; these requirements are documented on a per-function
54 basis.
55
56 \sa {Container Classes}
57*/
58
59/*! \typedef QPair::first_type
60
61 The type of the first element in the pair (T1).
62
63 \sa first
64*/
65
66/*! \typedef QPair::second_type
67
68 The type of the second element in the pair (T2).
69
70 \sa second
71*/
72
73/*! \variable QPair::first
74
75 The first element in the pair.
76*/
77
78/*! \variable QPair::second
79
80 The second element in the pair.
81*/
82
83/*! \fn QPair::QPair()
84
85 Constructs an empty pair. The \c first and \c second elements are
86 initialized with \l{default-constructed values}.
87*/
88
89/*!
90 \fn QPair::QPair(const T1 &value1, const T2 &value2)
91
92 Constructs a pair and initializes the \c first element with \a
93 value1 and the \c second element with \a value2.
94
95 \sa qMakePair()
96*/
97
98/*!
99 \fn QPair<T1, T2> &QPair::operator=(const QPair<T1, T2> &other)
100
101 Assigns \a other to this pair.
102*/
103
104/*! \fn bool operator==(const QPair<T1, T2> &p1, const QPair<T1, T2> &p2)
105
106 \relates QPair
107
108 Returns true if \a p1 is equal to \a p2; otherwise returns false.
109 Two pairs compare equal if their \c first data members compare
110 equal and if their \c second data members compare equal.
111
112 This function requires the T1 and T2 types to have an
113 implementation of \c operator==().
114*/
115
116/*! \fn bool operator!=(const QPair<T1, T2> &p1, const QPair<T1, T2> &p2)
117
118 \relates QPair
119
120 Returns true if \a p1 is not equal to \a p2; otherwise returns
121 false. Two pairs compare as not equal if their \c first data
122 members are not equal or if their \c second data members are not
123 equal.
124
125 This function requires the T1 and T2 types to have an
126 implementation of \c operator==().
127*/
128
129/*! \fn bool operator<(const QPair<T1, T2> &p1, const QPair<T1, T2> &p2)
130
131 \relates QPair
132
133 Returns true if \a p1 is less than \a p2; otherwise returns
134 false. The comparison is done on the \c first members of \a p1
135 and \a p2; if they compare equal, the \c second members are
136 compared to break the tie.
137
138 This function requires the T1 and T2 types to have an
139 implementation of \c operator<().
140*/
141
142/*! \fn bool operator>(const QPair<T1, T2> &p1, const QPair<T1, T2> &p2)
143
144 \relates QPair
145
146 Returns true if \a p1 is greater than \a p2; otherwise returns
147 false. The comparison is done on the \c first members of \a p1
148 and \a p2; if they compare equal, the \c second members are
149 compared to break the tie.
150
151 This function requires the T1 and T2 types to have an
152 implementation of \c operator<().
153*/
154
155/*! \fn bool operator<=(const QPair<T1, T2> &p1, const QPair<T1, T2> &p2)
156
157 \relates QPair
158
159 Returns true if \a p1 is less than or equal to \a p2; otherwise
160 returns false. The comparison is done on the \c first members of
161 \a p1 and \a p2; if they compare equal, the \c second members are
162 compared to break the tie.
163
164 This function requires the T1 and T2 types to have an
165 implementation of \c operator<().
166*/
167
168/*! \fn bool operator>=(const QPair<T1, T2> &p1, const QPair<T1, T2> &p2)
169
170 \relates QPair
171
172 Returns true if \a p1 is greater than or equal to \a p2;
173 otherwise returns false. The comparison is done on the \c first
174 members of \a p1 and \a p2; if they compare equal, the \c second
175 members are compared to break the tie.
176
177 This function requires the T1 and T2 types to have an
178 implementation of \c operator<().
179*/
180
181/*!
182 \fn QPair<T1, T2> qMakePair(const T1 &value1, const T2 &value2)
183
184 \relates QPair
185
186 Returns a QPair\<T1, T2\> that contains \a value1 and \a value2.
187 Example:
188
189 \snippet doc/src/snippets/code/doc_src_qpair.qdoc 2
190
191 This is equivalent to QPair<T1, T2>(\a value1, \a value2), but
192 usually requires less typing.
193*/
194
195/*! \fn QDataStream &operator>>(QDataStream &in, QPair<T1, T2> &pair)
196
197 \relates QPair
198
199 Reads a pair from stream \a in into \a pair.
200
201 This function requires the T1 and T2 types to implement \c operator>>().
202
203 \sa {Serializing Qt Data Types}
204*/
205
206/*! \fn QDataStream &operator<<(QDataStream &out, const QPair<T1, T2> &pair)
207
208 \relates QPair
209
210 Writes the pair \a pair to stream \a out.
211
212 This function requires the T1 and T2 types to implement \c operator<<().
213
214 \sa {Serializing Qt Data Types}
215*/
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